


gasoline

by aubadezayn



Series: TUMBLR PROMPTS [7]
Category: Supernatural
Genre: Crazy!Cas kinda, Dark!Dean, Dean in Panties, Dom!Cas, Light BDSM, M/M, Murder, Not as dark as it sounds though lmfao, Panties, Serial Killer Castiel, Sub!Dean, Top!Cas, bottom!Dean, dark!cas, donald trump gets killed how sad, leviathan!cas - Freeform, prostitutes mentioned, they will fuck in the second part
Language: English
Status: Completed
Published: 2015-09-04
Updated: 2015-09-06
Packaged: 2018-04-19 01:50:30
Rating: Explicit
Warnings: Graphic Depictions Of Violence
Chapters: 2
Words: 3,872
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4728272
Author URL: https://archiveofourown.org/users/aubadezayn/pseuds/aubadezayn
Summary: <blockquote class="userstuff">
              <p>You can't wake up, this is not a dream<br/>You're part of a machine, you are not a human being</p><p>my wife wanted leviathan!cas x demon!dean so i gave it to her. they fight, they fuck, they're in love.</p>
            </blockquote>





	1. before the fuck

**Author's Note:**

> CHECK ME OUT ON TUMBLR: [CASTIELADRIFT](http://castieladrift.tumblr.com)

There are moments, of lucidity, in which Castiel remembers that he was an angel. The darkness will fade and he'll be reminded that once he was singular, though now he is plural. I am also a we. Then the darkness will sink back over him and he'll be content to forget himself.

In the beginning (or is it the end?), there is always a strange man calling. Castiel does not remember him but he keeps the phone on when the man calls, and listens to him whine about coming "home" and a man named "Dean" missing. He's mildly amused for awhile, or at least the voices in his head are, but about a week after the first call Castiel smashes the phone under his foot. 

He has work to do.

"Sir! Sir, you cannot go in there!" A woman in a pantsuit chases after him as he strides through the gates of Donald Trump's mansion in Florida. She has a gun pointed at him and has called for extra security decal. Neither will work on him but it's nice to be feared. 

"Sir, stop right now or I will be forced to take you down!" She shouts, and he can almost hear the shaking of her hands. The voices in his mind are growing stronger, they whisper for him to kill, kill, KILL. His sensible shoes squeak on the marble floor as he turns around to face her.

She gasps, her gun dropping to the ground when her hands become too shaky to grip it. "Oh my god."

Castiel knows, distantly, what she's seeing. The veins of black reach up his neck, and they pop out under his eyes. Her eyes are bulging from fear, and she looks about to run away when suddenly there are 6 men flanking her with guns. 

His face splits into a huge grin and he laughs. His laughter sounds like nails on a chalkboard, like car wheels squealing on a wet road, like blood trickling out of a wound. 

No one makes it out alive, except for Castiel and his voices.

\----------

He's on the move, combing the Eastern Seaboard for sinners (and anyone else) to satiate his hunger with. There is a part of him, a little white spot of light inside, that cries when he tears theme apart but the majority of him grins and cackles. He finds himself laughing frequently, the sound bubbling out of him without his permission.

More frequently the voices become physical, and they move his limbs without him, they push against his skin straining to get out. He screams from the pain of it sometimes. Most of the time he likes it.

There's a group of prostitutes outside a dirty bar in South Carolina, but they're not Castiel's target. He'll gladly eat them later, but right now he has his eye on the biker gang paying them for their services. The men are big and beefy, and Castiel's teeth ache to bite in. He thinks in his past he had a very different face, but now he has a gaping maw desperate for food. The voices in his mind whisper that he, they, have been starved for too long.

He's nearly to the group when something catches his eye and he stops. The voices get angry and he can feel them pushing at his stomach, trying to get out. One of the prostitutes notices, and out of the corner of his eye he sees her abruptly walk away. A customer swears after her but she's smart, she knows the twenty dollars is not worth facing what she's just seen.

The person that caught his attention to begin with, is not as smart as the prostitute.

"Heya, Cas. How you doin'?" The man's eyes flicker to black, and though that is definitely not how he remembers him it triggers the realization in Castiel.

"Hello, Dean." Castiel grins, knowing the greeting will touch a sore spot. He's sorely disappointed when Dean's smile doesn't waver. "You're a demon now, you just can't let me have anything can you?" 

"More than enough _bad_ to go around." Dean's eyebrows wag up and down suggestively and his eyes switch back to green. 

"That might have been cute once to your fool of an angel, but right now you're standing between us and our dinner." Castiel could feel the veins of black spreading the more agitated he became, but Dean's grin never faltered. Becoming a demon had certainly hardened the man.

"So you are an us now? You and Leviathan signed the marriage contract already, got a dog and a picket fence?" Dean laughed, walking out of the shadows of the bar. 

He's wearing a maroon overshirt on top of a black shirt and he swaggers like ever step doesn't matter. Castiel's voices raise in volume and he ignores them in favor of gritting his teeth and thinking of a comeback.

Dean gets up close, unafraid and walks a circle around Castiel who has blackness on the verge of dripping from his eyes. "Why do you care, Winchester?" Castiel snaps, feeling cornered.

"Oh I don't, neither do you though. 'Cause you're not really you, Castiel would never be tearing people apart. He wouldn't have killed Donald Trump no matter how shitty the man was. He wouldn't be able to just stand there when I look like this." Suddenly Dean was in his face and his eyes were deep black. 

"Castiel was weak. We are not." Dean's face was within a few inches of Castiel's, and over the demon's shoulder Castiel could see the biker gang was gone. Most of the prostitutes were gone as well, with clients or moving on. "You should step back now."

"I'm not afraid of you."

"You should be." Castiel snarled, throwing Dean into the air and across the parking lot. The remaining sex workers screamed as they noticed Castiel's face and seen him throw Dean. He could have caught them, if he wanted to - his stomach gnawed with hunger, the voices inside him screaming to eat, but he let them go. 

He had a bigger fish to fry, as the humans said.


	2. dean needs it bad

**Summary for the Chapter:**

> the title is all that needs to be said, very desperate!sub!demon!dean.

**Notes for the Chapter:**

> CHECK ME OUT ON TUMBLR: [THORINSONOFDURIN](http://thorinsonofdurin.tumblr.com) I changed my url recently :)) THIS IS ALSO MY FIRST TIME WRITING FULL ON SEX, SO PLEASE BE KIND TO ME. 
> 
> ALSO THIS WAS WRITTEN FOR MY WIFE, CHECK HER OUT ON TUMBLR AT [LEGALLYDEAN](http://legallydean.tumblr.com)

The bar's parking lot was empty and the air seemed to drop in temperature as Castiel strode to stand above Dean. Blood ran down Dean's cheek from a large cut on his temple but he just laughed. "Fuck, Cas. I gotta say, last person that made me bleed...I got laid." Dean laughed, collapsing back onto the ground.

Castiel's loafer came down hard on Dean's sternum, causing the demon to choke on his own laughter. "I'll eat you alive, limb by limb. You miniscule-"

He hits the alley wall of the bar before any of him can register he's moved. Dean's forearm is jammed under his chin holding him in place.

Teeth barred, voice husky Dean gets close and lets his eyes flip to black. "Come on, Cassy," He whispers, his voice and breathe running over Castiel's lips. "Be creative, there's other ways to satisfy that hunger, you know."

"I will kill you. You are beneath us." Castiel whispered back, his body betraying him. The leviathan were not pleased with the proceedings but as his cock filled and heat ran up in his cheeks, they took a step back. He felt more lucid than usual but the darkness was not gone. He could still feel his body rejecting the leviathan, in the form of blackness in his veins.

"Then _put_ me beneath you." Dean whispered, his lips brushing Castiel's. Black eyes, black veins, they collided like two parts of the same darkness. Castiel's hands gripped the demon's hair in his hands, feeling the length on top slide between his fingers.

Their lips meet harshly, teeth colliding and biting into tender flesh. Dean's breath is heavy on Castiel's tongue. Dean pulls at Castiel's trenchcoat, the material dropping the dirty alley ground and quickly being accompanied by several buttons from his shirt. As a demon Dean seems faster and his hands are blur that even the Leviathan can't keep up with.   
Castiel manages to get a grip on the demon's overshirt and forces it down his arms. He stops pulling when it hits the top of Dean's arms and yanks it tight, forcing his arms down to his sides. Dean's eyes flash to green and back to black, but that one glimpse of green is enough to see his dilated pupils. "Fuck, Cas."

"I'm not Cas." Castiel insists, spinning them to shove Dean against the wall. Dean exhales sharply on impact and thrusts his hips forward, where they meet Castiel's. He groans despite himself, falling forward into Dean to bite hard at the point where his neck meets shoulder. His teeth ache to bite more, to feed, but his blood rushes for a different reason.

The shirt stays where it is, restricting Dean's motion, while Castiel devours the demon's mouth. He can feel Dean pushing against it, and the seams make tiny ripping sounds, but Castiel makes a decision before they can rip fully. He throws Dean down on the ground free from the shirt, and places his foot carefully on top of Dean's throat.  
The demon chokes and his eyes flash to green in panic. Castiel keeps his foot in place while he takes off his shirt, carefully folding it. Dean groans and Castiel smiles. "Patience." His voices know all about patience and waiting.

His vessel is handsome, he supposes. Though looking at his own body has never caused the type of feelings he's getting looking at Dean. His blood is pulsing through his body in a sickly rush, and his cock is hard in his slacks. Leviathan don't get hard, neither do angels. Yet, he is.

Castiel puts his hand on the button of his slacks but pauses there and smirks. "Beg."

"Fuck you." Dean bites, trying to pry Castiel's foot off his throat. Castiel applies a little bit more carefully controlled pressure and Dean's legs flail out in his struggle.

"You asked for me to put you beneath me, do you not enjoy it?" Castiel asks mockingly, his voice a touch off from singing.

"I kinda-" Dean breaks off, coughing and Castiel lifts up just a little bit. "I - uh sorta expected it to involve my dick a little more." The dick in mention is straining against Dean's denim jeans, begging for attention. But that's not enough, Castiel needs to hear it. He pulls a face and sighs.

"It can involve that, Dean, all you have to do is ask." Castiel toys with the button, popping it open with a sudden motion and Dean jumps under his foot. He can nearly see the demon break before him.

"Fuck, please, touch me." Dean begs, his voice barely a whisper over the sound of the bar. No one has come by the alley yet but even if they do, with a place like this they're not likely to interrupt. "Please, Cas."

Castiel is down on his knees before the voices in his mind can register it, straddling Dean's chest and pulling his zipper down. Jimmy wore underwear when he was taken, like a good religious man, but over the years Castiel hadn't bothered to recreate them when they got destroyed. Dean's eyes are drawn straight to where his dick is barely being held in by the slacks, and the demon's tongue runs wet over his own red lips.

"Suck. Now." Dean looks up at him and in the dark, Castiel can only see the barest glimmer of light on black eyes. Then there are lips pressing around the head of his dick, drawing him in and he can't see anything. Dean's mouth is hot and wet, and far more skilled than he would have imagined.

He moves up and down as best he can in their position, pulling his cheeks in and suctioning hard around Castiel. Moans bubble up out of Castiel's mouth, defying the voices inside but he can't hold them in. The hunger eases as the world narrows down to the feeling of Dean's mouth. " _Fuck_ ," He moans, throwing his head back and thrusting his hips forwards, the barest bit of Dean's teeth hitting him in surprise. It only adds to him losing his mind.

He looks down and Dean's watching him, eyes flickering between green and black like he's lost control of it. His hands are grasping tightly onto Castiel's thighs and even though it's so dark, Castiel knows the demon's lips are slick and bright red from the friction. Castiel thrusts forward slowly, testing Dean.

His blood boils briefly when Dean pulls off with a husky exhale and coughs. "You can." Castiel calms as Dean gets back to sucking him, one of his hands rubbing up Castiel's bare abdomen. They're both startled when Castiel's abdomen stretchs underneath Dean's hand, Leviathan scratching at his insides.

Dean yanks his hand back and twirls his tongue around the head of Castiel's dick. Overwhelmed by the Leviathan and pleasure warring inside him, the trick surprises Castiel enough to thrust fast and deep into Dean's mouth. He's about to pull out when Dean moans and grabs his ass, yanking him forward so his entire cock is swallowed.

Castiel growls, his head filled with the angry sounds of Leviathan and his cock throbbing. He thrusts forward and Dean gags but his hand is still pressing Castiel forward, so it must not be too bad. His hips pull back and push in of their own accord, desperation tightening in his groin. Dean pulls down the back of his slacks and his hand squeezes tight before coming down hard in a slap.

Castiel pulls out abruptly, hunching over to pant heavily against Dean's hair. The spank was unexpected but by far, no unwanted. The moment Dean's hand had collided with his skin, nerve endings had fired all along his spine. The Leviathan are silent and withdrawn as he sits back up straight.

His cock rests against Dean's cheek, a sticky strand of precum barely visible clinging to both. The demon's panting, hand still resting on Castiel's ass and eyes still flickering but with longer pauses.

"Beg." Castiel whispers, kissing Dean's cheek before continuing along the shell of the demon's ear. "Tell me what you want."

Dean's hand trails up Castiel's bare back to tangle into his hair. Lips press against his temple, and he hears " _I want you to fuck me._ "

Castiel has Dean's hands pinned to the gravel quickly and he looks the demon straight in the eye. "Good boy." He says, smirking. Dean full body shivers, Castiel can feel it on his own skin and it gives him immeasurable pleasure.

The first thing he sees is red, and for a second he thinks he's killed Dean and the red is in his mind. Then he realizes that it's lacy, and right on the head of Dean's cock, pressed down and contained, is a little bow.

"They're new so don't rip em." Castiel snaps to look at Dean and smirks in response to Dean's own cocky smile. Dean thrusts his hips up, rocking Castiel who sits heavy on his thighs. The cocky smile fades into an open mouthed breath when Castiel's hand lands lightly over his groin. The jeans are barely open but Castiel can feel the head leaking beneath his fingers, if he lifted his fingers surely the red panties would have a little stain.

"Did you do this when you were human?" Castiel asked, running one finger teasingly along the length, flicking the little bow. "Seems pretty _gay_." He sings.

"It's called bisexual, man and aren't you gonna get around to taking em off me?" Dean kicks up again, rocking Castiel.

"Hmm, I don't know. I like the way you look in them." He grips the jeans and yanks, pulling them down to mid thigh and exposing the rest of the lace. They're red as blood and cradling Dean's cock like they were made for it, though they're decidely feminine. Castiel lifts the edge above his thigh and sees a light red line where the elastic has dug in over time. He licks it, tracing the taste of Dean's skin.

"We don't got all night." Dean mutters, groaning as Castiel traces the top of the panties across his lower abdomen. "Come on, _please_." He thrusts up, the lace rubbing against Castiel's hand.

"I don't have lube." Castiel would bite Dean's head off and eat him for dinner, but there's no point in causing them both pain. He reaches into the panties and cups Dean's cock in his palm, massaging the head with his fingers.

The obscenity gets punched out of Dean, " _Fuck_! I do, in my, fuck in the impala." Castiel continues jerking Dean off, pressing wet kisses to all the places he couldn't when they were human. The freckles on Dean's shoulders, the crease of his thigh, the tender flesh under his belly button - all those places Castiel couldn't touch, _they_ get to touch now.

Castiel zaps them to the impala and presses the demon down face first on the hood. "Fuck! Cold!" Dean shouts, writhing away from the metal. Castiel shushes him softly, pulling Dean into his chest with a strong hand on the demon's throat. He shoves his other hand into Dean's panties and jerks him fast, hand moving in a blur underneath the red.

"Oh my-" Dean's shaking in his arms, throat moving frantically as he gasps in air. Just as his muscles start to tense and Castiel can hear him going silent and high pitched, he lets go and moves away.

"Ugh," Dean groans, collapsing onto his hands against the impala and panting. He glares with black eyes as Castiel moves to open the impala and reach into the glove department. "Seriously, fuck you."

"You would like to, wouldn't you? You should be nice to me, I could kill you right here and leave you to be found in women's panties and without a head." Castiel pops open the lube bottle and squeezes some onto his fingers. Dean shivers, and though he tries to hide it behind a glare, Castiel still sees.

He moves back behind Dean and pulls the panties down below his ass cheeks. They're large enough to keep the panties down and the elastic actually makes his ass look better. Dean shuffles on his feet and Castiel does what seems appropriate.

Dean's ass jiggles mesmerizingly when Castiel slaps it, and the moan Dean lets out is definitely worth it. "Just fucking do it, Cas. Stop playing around." He demands, thrusting his hips back and hitting Castiel's lubed up fingers.

"Fine," Castiel snarls into Dean's ear, pressing forward and inside. Dean seizes up immediately around the fingers, like he hadn't just been begging for Castiel to finally be inside. The Leviathan whisper for him to just keep going, disregard, but Castiel is independent enough to wait, giving Dean a moment before he starts pushing in further.

It's a long process, fingering Dean open takes patience which Castiel has in abundance. He strokes Dean lazily, the demon's cock hard as stone. He laves kisses along Dean's neck and shoulders, biting down hard on certain spots and startling loud moans. At one point, when he's three fingers deep and thinking soon he'll be able to get inside he brushes a spot and Dean's back snaps into an arch that could be measured. The demon's breath comes out in a husky gasp and he moans Castiel's name like he's praying to God.

"Fuck me, Cas, come on. I'm good." Dean's hand comes down hard on the impala's hood, like he's tapping out, so Castiel removes his fingers. He pulls his own slacks down further and spreads more lube onto his cock, which is bright red with a desperate purple head just begging to be inside. When he's wet enough he positions himself and places his other hand firmly on Dean's lower abdomen, then he pushes them together.

Dean whines, hand flying back to grip in Castiel's hair. "Oh my God." Castiel pushes forward slowly, eyes shutting as the world around him explodes. Dean is still so tight, he could suffocate in this man. When the head finally pops inside, they both shudder, their goosebumps pressing against each other. Castiel's hand slowly slides back and forth across Dean's pelvis, soothing the ache.

Castiel is finally all the way inside, his hips pressed against Dean's ass tightly, and he can't help but groan. The Leviathan are silent, but he can still feel their rage in his veins. He wonders if there's blackness running down his eyes, he can't be sure.

He pulls back curiously and Dean groans but doesn't try to stop him, so he continues thrusting slowly. As an angel he'd never had sex, and as a Leviathan he was too busy eating, but now the pleasure crawls up his spine and overwhelms him. He speeds up a little bit, his hips slapping against Dean loudly but not nearly as loud as Dean's moans.

" _Fuck, Cas. Faster._ " Dean demands, the impala already rocking with the force of Castiel's thrusts.

Castiel speeds up, the friction driving him mad. He reaches around Dean and strokes his hand over the panties, feeling the lace shifting under his hand. He jerks Dean over them, feeling the wetness from the tip through the fabric.

Dean's getting louder but thinner at the same time, all of his moans breathier and higher pitched than at the start. His back is arched so tight that the only points of connection with Castiel are at his shoulders and his ass.

"Are you close?" Castiel huskily groans into Dean's ear as he starts to lose his rhythm. There's a spot in his abdomen that feels like a coiled spring, and his cock is so hard he's pretty sure the Leviathan are only quiet because there's not enough blood in his head. Dean can't speak, according to the heaving gasps he's taking he can barely breathe, but he nods frantically, head falling backwards onto Castiel's shoulder.

The moment Dean nods, Castiel drops one hand to stroke his cock and the other to slap his ass. The stimulation overwhelms him and Dean seizes up, shouting Castiel's name into the night and cumming all over the impala's hood.

Castiel keeps going, fucking him through it and Dean whines. Castiel is so close, he just needs a final push. He needs _something_ -

"Come, Cas. Please, I can't-"

He cums harder than he imagines anyone has ever come. The world implodes until the only thing left is Dean and him. The Leviathan and their darkness seems lightyears away. Castiel's arms wrap tightly around Dean's middle and pull him back against his chest.

He pulls out with an awkward sound, and Dean immediately collapses to sit on the impala's hood. "Wow." Dean whispers, eyes flipping to green and staring at the sky.

"Yes that was...more than I expected from tonight." Castiel mused, tucking himself back into his pants. He sat down on the impala with Dean, feeling oddly satisfied, not hungry at all.

"We should have became bad a long time ago." Dean laughed, smiling and flashing Cas his black eyes. Castiel laughed along, feeling the darkness start to spread in his veins again.

 

**Notes for the Chapter:**

> COMMENTS MUCH APPRECIATED, THANK YOU FOR READING!

**Author's Note:**

> COMMENTS MUCH APPRECIATED, THANK YOU FOR READING!


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